Watcher is built as a plugin for the Fiddler HTTP debugging proxy available at www.fiddlertool.com.
Fiddler provides all of the rich functionality of a good Web/HTTP
proxy. With Fiddler you can capture all HTTP traffic, intercept and
modify, replay requests, and much much more. Fiddler provides the HTTP
proxy framework for Watcher to work in, allowing for seamless
integration with today’s complex Web 2.0 or Rich Internet Applications.
Watcher runs silently in the background while you drive your browser and
interact with the Web-application.